by David Allen

About: David Allen

I am currently working in sunny England as a Chemistry teacher.
Previously, I worked at the United World College of South East Asia (UWCSEA) in Singapore from August 2000 - July 2008. There, I taught HL & SL Chemistry, STS SL (school based syllabus) and TOK. Other responsibilities included Head of Year and Assistant Houseparent.
My IB work entails being an examiner for SL or HL Chem Paper 2 or 3 and I moderate IA.

Recent Posts by David Allen

Global warming is still a topic that stirs a range of emotions in people. Is it real? Is it made up? Is it something to worry about or not? Will it actually affect you?
But, love it or hate it, the topic is not going to go away.
We have just had some training on how to teach this and I thought it was worth sharing with you.
Take the premise 'Global Warming is going to cause more extreme weather patterns'.
Then, think of the ...

We have just had some great INSET on 'Visible Thinking Routines'. To be honest, I thought this was going to be some complicated and difficult 'new' way of teaching things (apologies for my skepticism) but as the session went on I came to realize that yes, it was something new for me to think about and do but it wasn't at all complicated. In fact, many of the ideas used I already use myself anyway: the INSET session just helped me ...

When I started teaching (22 years ago) differentiation was the buzz word. We had extensive lectures on it in my teacher training qualification, and the schools I carried out my teaching practice in were ensuring that all of their lessons were ‘fully differentiated’.
Invariably, this meant having three worksheets up your sleeve, an easy, medium, and difficult one. You would then give students a worksheet according to their ability (this was labelled differentiation by task).
There was also differentiation by outcome, where ...

The topic of acid deposition can be found in the SL section of the acids and bases unit, section 8.5.
As a teacher, when I first read this title I had no idea what it meant, but, as with most things in the IB, the title is actually quite descriptive, once you know what the title means.
The key word is ‘deposition’. It means (according to the definition in the online dictionary by Merriam-Webster), simply, ‘the act of being deposited’.1
So acid deposition ...

How do you teach about the halogens?
I am in the middle of teaching about them and thought it was worth telling you how I introduce the topic. I do like this topic as it provides lots of opportunities to link together parts of the course.
Firstly, I will start with some theory, things such as the fact that the halogens are diatomic and are the only group whose members exist as solids, liquids and gases at room temperature.
This then leads into ...

The concept of superacids was a new on to me until the other day when I read about a chemistry competition that had been held in Moscow earlier this summer. You may have been in this very competition so, if you had, and I get something wrong, please do put me right!
The competition asked students to 'design' (on paper) an alien blood that resembled the blood in the 'Alien' movies. If you recall, this blood needed to be capable of ...

I've just taught this topic and thought it was worth sharing my ideas as to how I introduced the topic and concept of equilibrium.
Firstly, something worth considering before you launch into the topic is when do you teach it? In my opinion it needs to go after energetics. This is because some of the concepts need a good understanding of exothermic and endothermic reactions before one can decide on the effect of temperature on the position of equilibrium. It could ...

Equilibria can be a tricky concept to understand. In order to understand it, you need a good idea of reversible reactions and then a good idea of a dynamic equilibria.
So, what is a reversible reaction?
Put simply, it is a reaction in which products can be turned into reactants, but reactants can also be turned back into products.
This can be shown using the ⇌ symbol:
Reactants ⇌ Products
For example, ammonium chloride will thermally decompose into ammonia and hydrogen chloride gases, but these gases will ...

I’ve just started teaching the kinetics topic to my students and so far we have focussed on the collision theory. Have you heard of this?
The collision theory explains to us what happens during chemical reactions in terms of the collision of particles.
In order for a chemical reaction to occur, particles need to come together (collide) with sufficient energy (speed). This is called the activation energy (and is defined as the minimum amount of energy required for a chemical reaction). If ...

We carried out a great lab in school today, making esters. Have you ever done this? What was good about it was that we used a good range of reagents and got some very different results.
I set the class up with a range of alcohols and carboxylic acids and told them it was up to them what they wanted to make.
We used microscale quantities for two important reasons:
1, As a safety precaution
The beauty of using the microscale quantities is that ...